Summary of Charges Incurred and Reserves Recorded in Connection with Restructuring and Relocation Programs by Segment (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 2011 Restructuring Program	Dec. 31, 2011 2011 Restructuring Program	Dec. 31, 2012 2011 Restructuring Program Residential Real Estate	Dec. 31, 2011 2011 Restructuring Program Residential Real Estate	Dec. 31, 2012 2011 Restructuring Program Commercial Real Estate	Dec. 31, 2011 2011 Restructuring Program Commercial Real Estate	Dec. 31, 2012 2011 Restructuring Program Rural land	Dec. 31, 2011 2011 Restructuring Program Rural land	Dec. 31, 2012 2011 Restructuring Program Forestry	Dec. 31, 2011 2011 Restructuring Program Forestry	Dec. 31, 2012 2011 Restructuring Program Corporate and other	Dec. 31, 2011 2011 Restructuring Program Corporate and other	Dec. 31, 2012 2010 and prior restructuring and relocation programs	Dec. 31, 2011 2010 and prior restructuring and relocation programs	Dec. 31, 2012 2010 and prior restructuring and relocation programs Residential Real Estate	Dec. 31, 2011 2010 and prior restructuring and relocation programs Residential Real Estate	Dec. 31, 2012 2010 and prior restructuring and relocation programs Commercial Real Estate	Dec. 31, 2011 2010 and prior restructuring and relocation programs Commercial Real Estate	Dec. 31, 2012 2010 and prior restructuring and relocation programs Rural land	Dec. 31, 2011 2010 and prior restructuring and relocation programs Rural land	Dec. 31, 2012 2010 and prior restructuring and relocation programs Forestry	Dec. 31, 2011 2010 and prior restructuring and relocation programs Forestry	Dec. 31, 2012 2010 and prior restructuring and relocation programs Corporate and other	Dec. 31, 2011 2010 and prior restructuring and relocation programs Corporate and other
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period											$ 782		$ 337		$ 186		$ 149				$ 110		$ 790	$ 960	$ 4	$ 239		$ 9		$ 36		$ 19	$ 4	$ 657
Cost Accrued	(91)	18	18	55	797	348	5,926	4,476	11,547	5,251	(106)	10,932	(20)	623	(186)	1,660	(145)	208		77	245	8,364		11,551	(4)	76		(3)		(12)			110	558
Payments											631	10,150	317	286		1,474	4	59		77	310	8,254	745	11,721		311		6		24		19	114	1,211
Balance at end of period											45	782		337		186		149			45	110	45	790		4								4
Cumulative Charges											$ 10,825		$ 603		$ 1,474		$ 63		$ 77		$ 8,608		$ 48,715		$ 19,550		$ 1,344		$ 2,554		$ 494		$ 13,948